Settlers first occupied the pioneer settlement now known as West Linn in the early 1840s when Robert Moore purchased 1,000 acres of land from the "Wallamut" (Willamette) Indians. He built his cabin high on a slope overlooking the Willamette Falls and set about building a town, calling it “Robin's Nest.” The town was situated on property now occupied by the West Linn Paper Company.
By 1846, Moore had built four flour and lumber mills, along with dwellings for the mill workers. He also operated a ferry to Oregon City. In 1845, Moore renamed the tiny town “Linn City” in honor of his friend, well-known free-state advocate Dr. Lewis F. Linn, a U.S. Senator from Missouri and sponsor of the Donation Land Claim Bill. Moore became Linn City’s first postmaster in 1850, and purchased The Spectator, an Oregon City newspaper, in 1852. By then, his Linn City enterprises included a gristmill, sawmill, warehouse, wharves, and a breakwater to create a basin for boats to load and unload cargo. Moore died in 1857.
Not long after Moore's death, a fire destroyed the sawmill, gristmill, wharves, and a docked steamer ship. Local businessmen began to rebuild, only to see their hard work washed away in floods later that same year.
In 1868, Linn City was revived when the Willamette Transportation Locks Co. began providing passage to shipping over the Willamette Falls. The locks remained in continuous operation until placed in "non operational" status by the Army Corps of Engineers in 2011.
In 1913, the City of West Linn was incorporated, encompassing West Oregon City, Bolton, Sunset and Willamette Heights. The incorporation allowed the settlements to obtain needed services, utilities, and improvements without annexing to Oregon City. After considerable debate on a name, the city founders decided to honor the pioneer town that Moore had established.
The city's population historically grew steadily, but in recent years has leveled off. The 1860 census listed 225 residents. By 1920, the number had grown to 1,628. The 1960 census set the population at 2,923, and by 1970, West Linn had grown to more than 7,000. The city’s population has continued to grow each year. Currently, the city’s population is 25,992. The Portland State Population Research Center estimated zero population growth in West Linn between 2006 and 2007.